NSNull integerValue: Unrecognized Selector - Flutter IOS only-CodePudding

TL;DR

I am getting an error only on IOS physical device when tapping certain buttons that excecute a certain line of code. I need to interpret the error and find the cause (why only on physical device?)

I am getting this error:

-[NSNull integerValue]: unrecognized selector sent to instance 0x2069e0558 *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[NSNull integerValue]: unrecognized selector sent to instance 0x2069e0558' *** First throw call stack: (0x1ac9d1288 0x1c5701744 0x1acaaefc0 0x1ac965e98 0x1ac964f70 0x102e9aff0 0x106b80b14 0x10666ba8c 0x1ac636e6c 0x1ac638a30 0x1ac646f48 0x1ac646b98 0x1ac989800 0x1ac943704 0x1ac956bc8 0x1c8ac2374 0x1af2cab58 0x1af04c090 0x10265d384 0x102cb1da4) libc abi: terminating with uncaught exception of type NSException

thread #1, queue = 'com.apple.main-thread', stop reason = signal SIGABRT frame #0: 0x00000001e4474b38 libsystem_kernel.dylib__pthread_kill 8 libsystem_kernel.dylib__pthread_kill: -> 0x1e4474b38 < 8>: b.lo 0x1e4474b58 ; < 40> 0x1e4474b3c < 12>: pacibsp 0x1e4474b40 < 16>: stp x29, x30, [sp, #-0x10]! 0x1e4474b44 < 20>: mov x29, sp Target 0: (Runner) stopped.

Whenever I excecute the following Provider code on the tap of a button:

List<FrediUser>? allFrediUsers = Provider.of<List<FrediUser>>(context);

The actual code seems to have nothing to do with the error, it just triggers it.

Important Notes

This behaviour ONLY HAPPENS ON iPhone PHYSICAL DEVICE.
Works in iPad PHYSICAL DEVICE.
IOS SIMULATOR works as expected
Works perfectly on android --> This means that there is no error with the provider package nor the code that is looking for that list.

I just need to interpret the error to know what it is exactly! All help wanted!

CodePudding user response：

My solution to this maddening use of NSNull by JSON interpreters is to create a category on NSNull, where I define integerValue, floatValue, length, etc - return 0 for all. Everytime you get another crash add a new category. I think I had 6 or 7 when I had this issue.

The problem with NOT doing this is you have to look for the NULL everywhere in your converted objects - a PITA in my opinion.

EDIT: the code I'm using, all in a NSNull JSON.m file:

@interface NSNull (JSON)
@end

@implementation NSNull (JSON)

- (NSUInteger)length { return 0; }

- (NSInteger)integerValue { return 0; };

- (float)floatValue { return 0; };

- (NSString *)description { return @"0(NSNull)"; }

- (NSArray *)componentsSeparatedByString:(NSString *)separator { return @[]; }

- (id)objectForKey:(id)key { return nil; }

- (BOOL)boolValue { return NO; }

@end

EDIT2: Now in Swift 3:

extension NSNull {
   func length() -> Int { return 0 }

   func integerValue() -> Int { return 0 }

   func floatValue() -> Float { return 0 };

   open override var description: String { return "0(NSNull)" }

   func componentsSeparatedByString(separator: String) -> [AnyObject] { return [AnyObject]() }

   func objectForKey(key: AnyObject) -> AnyObject? { return nil }

   func boolValue() -> Bool { return false }
}